Ripley's Believe It or Not by Ripley’s Believe It or Not! for January 11, 2000

The wikipedia page is quite interesting, but unfortunately it also disputes the above Mr. Ed item. Re: Bamboo Harvester’s trainer was Les Hilton. To create the impression that Ed was having a conversation, Hilton initially used a thread technique he had employed for Lubin’s earlier Mule films; in time, though, this became unnecessary. As actor Alan Young recounted: “It was initially done by putting a piece of nylon thread in his mouth. But Ed actually learned to move his lips on cue when the trainer touched his hoof. In fact, he soon learned to do it when I stopped talking during a scene! Ed was very smart.”18

Reports circulated during and after the show’s run that the talking effect was achieved by crew members applying peanut butter to the horse’s gums. Alan Young said in later interviews that he invented the story. "Al Simon and Arthur Lubin, the producers, suggested we keep the method [of making the horse appear to talk] a secret because they thought kids would be disappointed if they found out the technical details of how it was done, so I made up the peanut butter story, and everyone bought it